23 CHARACTERISTICS OF SELECTED PHYSICOCHEMICAL INDICES OF UPLAND CARBONATE STREAM WATER WITH COARSE-GRAINED SUBSTRATE

Hydrochemical research was conducted in 2011 at three measurement-control points on the Sztoła river, a left-bank tributary to the Biała Przemsza river. Water temperature and pH, dissolved oxygen concentration, oxygen saturation and electrolytic conductivity were measured directly in the field. 11 selected physicochemical indices of the Sztoła surface water were assessed in the laboratory. The analysis of the research results revealed that the water of the Sztoła along the analyzed river reach was first class quality. The analysis of water usable qualities proved that at point 1 it can be used for water supply after high-performance physical and chemical treatment, whereas at other points after a typical physical and chemical treatment, due to high manganese concentrations. Water does not meet the requirements of natural habitat for the Salmonoid fish only at point 1 because of exceeded standard values for nitrites. The Cyprinid fish have the proper habitat conditions along the examined river reach. Among 15 analysed physiochemical indices of water, 7 were statistically higher in the lower course, but they did not affect worsening of the Sztoła river water quality. Greater water pollution in the central and lower river reach is caused by the anthropogenic pressure connected mainly with the operations of extraction industry in the catchment.


INTRODUCTION
Water quality is determined by many natural factors, such as: topography, soil properties, intensity of lack of atmospheric [Xiao et al. 2014] and anthropogenic precipitations [Kanownik et al. 2013], which contribute to a considerable water loading with nutrients [Wang et al. 2014], pesticides, fertilizers [Monaghan et al. 2005] and other inorganic and organic substances [Wilcock et al. 2006].Agricultural and forest land management influence water quality [Pierzgalski et al. 2005, Grajewski et al. 2009, Grzywna 2014], as nitrogen and phosphorus supplied with surface runoffs contribute to eutrophication and degradation of waters [Cooper and Thomsen 1988, Mc-Dowell and Wilcock 2004, Rodgers et al. 2010].
Pollution from point sources [Policht-Latawiec et al. 2013] is far easier to document in comparison with the area pollution [Kanownik and Pijanowski 2007], which greatly contribute to water contamination in the catchment [Alexander et al. 2002, Piirainen et al. 2013].Therefore, an assessment of the efficiency of catchment management policy is so important [Ferraz et al. 2013], especially based on increasingly better applications for modelling and forecasting ecological hazard to waters, including both climatic and anthropogenic factors [Lai et al. 2013].Understanding ecological processes is very important for sustainable management of surface and ground waters in a catchment [Di and Cameron 2005].

MATERIAL AND METHODS
The hydrochemical research of the Sztoła river, situated in the north-western part of the Malo-polska voivodeship was conducted in 2011.The Sztoła river, 13.4 km long and with catchment area of 154km 2 is a left bank tributary of the Biała Przemsza.According to the abiotic typology it belongs to an upland carbonate stream with coarsegrained substratum.The riverhead is located at the foot of Kozłowa Góra hill in the area of the Olkusz Upland.Initially the river flows in a deep valley in the area of Dolinki Krakowskie Landscape Park towards north-west and several kilometers further flows into "Leśny Dwór" reservoir in Bukowno.The headwater section is almost totally devoid of water because of depression pit formed as a result of the operation of the zinc and lead mines in Olkusz, but also due to drainage of sand deposits exploited by the Szczakowa opencast mine.The Baba watercourse, originating near Olkusz, inflows to the Sztoła river in Bukowno.The watercourse is not fed by the primary springs, which are totally dry, but almost in 100% by the mining wastewater from the Pomorzany Mine in Olkusz.From Bukowno the Sztoła river flows to the west through pine forests, strongly meandering, in some places forming inaccessible wetlands and finally flows into the Biała Przemsza in Sławków.
Water for the analyses was sampled in 3 measurement-control points: point 1 at km 13+250, point 2 -at km 10+040, point 3 -at km 7+370 of the watercourse (Figure 1).The upper part of the catchment is almost wholly managed as a forest land, whereas residential areas and mining industry centres are located only below point 2 and these may pose a potential pollution hazard to the analyzed river.
Assessments of water quality indices of the Sztoła river were conducted using referential methods [Rozporządzenie MŚ 2011b].In the field pH was determined by CP-104 pH meter, electrolytic conductivity (EC) by CC-102 conductometer and the water temperature, dissolved oxygen contents and degree of oxygen saturation using CO-411 oxygen meter.The following assessments were made in the laboratory: soluble solids by evaporation, sulphates (SO 4 2-) by precipitation method; Ca 2+ , Mg + , Mn 2+ ions and Fe 2+ , Fe 3+ (total iron) using atomic absorption spectrometry (ASA) on UNICAM SOLAR 969 spectrometer.Ammonium (N-NH

RESULTS
During the period of investigations water temperature in the Sztoła river ranged from 7.3 to 14.9 o C and its pH from acid (pH 6.6) to alkaline (pH 8.3).Electrolytic conductivity did not exceed 582 μS•cm -1 and concentration of soluble solids was a maximum of 488 mg•dm -3 (Table 1).These values were lower than the limit values for water quality class I, which evidences a low mineral pollution of water.During the whole period of the investigations water at the analyzed river reach was characterized by very good oxygen conditions -the saturation level was over 100% and did not exceed 133%, whereas dissolved oxygen concentration was higher than 7 mg•dm -3 .Low concentrations of nitrites and nitrates were registered along the whole length of the analyzed watercourse, whereas ammonium nitrogen and phosphates occurred in trace amounts.The values of biogenic indices fell within the water quality class I [Rozporządzenie MŚ 2011a].Salinization of the analyzed Sztoła reach was on a low level; the highest sulphate concentration (SO 4 2-) was 113 mg•dm -3 , chloride (Cl -) -25 mg•dm -3 , calcium (Ca 2+ ) -155 mg•dm -3 and manganese (Mg 2+ ) -30 mg•dm -3 .The highest total iron concentration (0.36 mg•dm -3 ) was registered in point 1, but its mean value was the lowest, reaching 0.10 mg•dm -3 .In other points total iron concentrations did not exceed 0.30 mg•dm -3 , with the mean value of 0.13 mg•dm -3 .Concentration of manganese (Mn 2+ ) fluctuated from 0.01 to 0.12 mg•dm -3 and an average value of the concentration along the whole watercourse length did not exceed 0.04 mg•dm -3 (Table 1).
Assessment of the water usability for drinking water supply revealed that among the 18 analyzed indices, only 12 have been included in  1).High concentration of total iron and manganese makes difficult the Sztoła river water treatment for consumption.The highest manganese concentration -0.12 mg•dm -3 was registered at point 1.It caused that the Sztoła river water could be drawn for drinking water supply to people after a high performance physical and chemical treatment (category A3).At the other analyzed points, the river water would require a typical treatment (category A2).Maximum total iron concentration (0.36 mg•dm -3 ), like in case of manganese, occurred at point 1.Water of the Sztoła river at this point fulfilled the requirements for category A2 and would need only a typical physical and chemical treatment.At the other two points the water was in category A1.High concentrations of these metals in watercourses is typical for the surface waters of the Malopolska voivodeship.Their origin is natural and connected with the geological structure of the catchment, chemical composition of the rocks and soils in the catchment, and the river beds [Kanownik et al. 2013].
At measurement-control point 1, the Sztoła river waters did not meet the requirements for the salmonoid fish habitat due to exceeded admissible value of nitrites (0.01 mg•dm -3 ) [Rozporządzenie MŚ 2002b].On the other hand for cyprinids all analyzed indices meet the requirements for the freshwaters which are the habitats for these fish (Table 1).
Statistical analysis conducted using Mann-Whitney U test revealed that values of a majority of the tested indices differed significantly between points (Table 2).
Statistically lower values of pH, nitrates, electrolytic conductivity, soluble solids, chlorides, sulphates and calcium were registered, as well higher concentrations of magnesium in the upper course of the stream (point 1) in comparison with its lower course (points 2 and 3).* Statistical values in bold mean statistically significant differences at p < 0.05.

CONCLUSIONS
1. On the basis of the analyzed physicochemical indices supporting biological elements the ecological state of water along the examined length of the Sztoła river was determined as very good.
2. The Sztoła river water may be used for drinking water supply for people, however, due to high concentrations of manganese and total iron, it must be subjected to an appropriate physical and chemical treatment.
3. In the headwater part of the Sztoła river, its water does not fulfill the requirements for the salmonoid fish habitat because of exceeded nitrite concentrations.Along the whole length of the analyzed watercourse, the cyprinid have proper habitat conditions.
4. Among the 15 analyzed physicochemical water indices, values of 7 were statistically higher in the upper course of the river due to a higher anthropopressure, mainly due to the mining industry.However, it did not affect worsening of the Sztoła river water.

4 +)
and nitrate (N-NO 3 -) nitrogen concentrations, as well as phosphates (PO 4 3-) and chlorides (Cl -) were assessed by means of colorimetric flow analysis on FIAstar 5000 apparatus.Concentrations of NO 2 -and NO 3 -ions were computed from the nitrogen forms assessed in the laboratory.Elaboration of the results comprised determining the minimum and maximum values of individual indices and computing the arithmetic means.Statistical inference about the significance of differences of indices values between the measurementcontrol points was conducted by means of nonparametric Mann-Whitney U test on the significance level α = 0.05.The test was chosen because of the lack of distribution normality for a majority of analyzed indices, according to the results of Shapiro-Wilk test and the lack of the equality of variance determined by the Fisher-Snedecor test.Water quality was assessed according to the Decree of the Minister of the Natural Environment dated 9 November 2011 [Rozporządzenie MŚ 2011a], whereas the usable values -by comparison of the assessment results with the values admissible for water intended for water supply to people [Rozporządzenie MŚ 2002b] and for fish habitat under natural conditions [Rozporządzenie MŚ 2002a].

Figure 1 .
Figure 1.Location of measurement-control points in the Sztoła river catchment

Table 1 .
Range and mean values of analyzed physicochemical indices and quality class, and usable value of the Sztoła river water

Table 2 .
Significance of differences of water indices among the individual measurement-control points -difference between medians and probability of Mann-Whitney U test